Power line coding has become an interesting way to control devices without the need for additional control wiring. One example where power line coding has been proposed is in mains lighting.
Lighting fixtures have been designed that are capable of receiving control signals for controlling one or more aspects thereof. For example, some lighting fixtures receive control signals that may at least selectively dictate the dimming levels of such lighting fixtures.
One previous solution for transmitting such control signals utilized one or more stand-alone control wires that extend from a controller to the lighting fixtures. Data packets were then sent over the control wires to control the lighting fixtures. The data packets and communications may conform to a communications protocol such as DMX or DALI. Implementation of such a solution requires the running of one or more separate wires and involves limitations on wiring length and/or wiring method that may not be appropriate for certain applications such as street lighting.
Other previous solutions enable transmitting such control signals without installing new wires. For example, some solutions utilized wireless control signals or communications over the power wires. However, implementation of such solutions requires specific hardware modems and/or radios to be installed at each individual lighting fixture. Such specific equipment is often overly costly and/or may not be easily installed in existing lighting fixtures or light poles supporting lighting fixtures.
WO 2013/061206 discloses a power line coding method, described in connection with an application to lighting fixtures, in which a transformer is switched into or out of circuit to provide a voltage change (thereby implementing an amplitude modulation) which encodes a control signal. This provides a simple encoding method and enables decoding with simple decoding hardware and software.
Providing the desired voltage change consumes power and any power saving measures are of interest.